Thank you for your comments and info! It is very appreciated! : ) I just thought maybe it was some kind of artifact because it was the only one of its kind on the bank and both ends are a bit warn looking. Also, maybe you can help me with this....it has a different sound to it when I hit another rock up against it. It's a crisp ring sound unlike most rocks that sound more dulled. I don't know if that could tell me anything about it.